point2.c

来自「C源码集」· C语言 代码 · 共 56 行

#include <stdio.h>

int main (void)
{
	int i = 10, j = 7, k;
	int *p = &i;
	int *q = &j;
	int **pp = &p;

	printf("             i     j    k        p            q            pp\n");
	printf("start        %i    %i    %i     %p   %p   %p\n",
					i, j, k, p, q, pp);

	**pp += 1;

	/* pp points to p which points to i and i = i + 1
		so now i = 11                                  */

	printf("**pp += 1    %i    %i    %i     %p   %p   %p\n",
					i, j, k, p, q, pp);

	*pp = &k;

	/* whatever pp points to, make that point to the address of k
		so now p points to k                           */

	printf("*pp = &k     %i    %i    %i     %p   %p   %p\n",
					i, j, k, p, q, pp);

	**pp = *q;

	/* pp points to p which now points to k, make k = contents of q
		so k = j = 7                                   */

	printf("**pp = *q    %i    %i    %i     %p   %p   %p\n",
					i, j, k, p, q, pp);

	i = *q * **pp;

	/* make i = what q points to times what p points to
		so i = j * k = 7 * 7 = 49                     */

	printf("**i=*q***pp  %i    %i    %i     %p   %p   %p\n",
					i, j, k, p, q, pp);

	i = *q / **pp;

	/* make i = what q points to divided by what p points to
		so i = j / k = 7 / 7 = 1                       */
	printf("i=*q/**pp     %i    %i    %i     %p   %p   %p\n",
					i, j, k, p, q, pp);



	return 0;
}